Correlator; Figure 16-4 Bitbuf Memory; Table 16-6 Functions Using The Bit Buffer - Motorola DragonBall MC9328MX1 Reference Manual

Bluetooth Accelerator (BTA)
Bit 63
Word 3 (16 bits)
Bit 127
Word 7 (16 bits)
Bit 191
Word 11 (16 bits)
Bit 255
Word 15 (16 bits)
Bit 319
Word 19 (16 bits)
Bit 383
Word 23 (16 bits)
Bit 447
Word 27 (16 bits)
Bit 511
Word 31 (16 bits)
The BTA uses time sharing to minimize the amount of hardware required. Time sharing of the bit buffer is
feasible because the functions requiring the module are active at different times during a receive or
transmit function. Table 16-6 lists the uses of the bit buffer and the number of bits used for each function.
The order is chosen so that the first function in the table function is the first in time to be executed.
Encryption initialization
Users must never access the contents of the bit buffer during the encryption initialization or correlation
phases.

16.3.1.5 Correlator

The correlator performs correlation using eight times oversampling of the incoming bit stream to extract
the bit timing information and correlates against the 64-bit access code. The access code is written by
software to BTA registers SYNCH_WORD_0, SYNCH_WORD_1, SYNCH_WORD_2, and
SYNCH_WORD_3.
The threshold for the correlator is programmable via the THRESHOLD register. The correlation peak
value in the most recent correlation window can be read from the same register.
Software access to the bit buffer is prohibited during correlation because of the bit buffer time sharing (see
section 16.3.1.4).
16-12
LW0 (64 Bits)
Word 2 (16 bits)
LW1 (64 Bits)
Word 6 (16 bits)
LW2 (64 Bits)
Word 10 (16 bits)
LW3 (64 Bits)
Word 14 (16 bits)
LW4 (64 Bits)
Word 18 (16 bits)
LW5 (64 Bits)
Word 22 (16 bits)
LW6 (64 Bits)
Word 26 (16 bits)
LW7 (64 Bits)
Word 30 (16 bits)
Figure 16-4. BitBuf Memory
Table 16-6. Functions Using the Bit Buffer
Function Buffer Size (Bits)
Correlation
Receive
Transmit
MC9328MX1 Reference Manual
Word 1 (16 bits)
Word 5(16 bits)
Word 9 (16 bits)
Word 13 (16 bits)
Word 17 (16 bits)
Word 21 (16 bits)
Word 25 (16 bits)
Word 29 (16 bits)
Transmit
128 Used
512 Not used
512 Not used
512 Used
Bit 0
Word 0 (16 bits)
Bit 64
Word 4 (16 bits)
Bit 128
Word 8 (16 bits)
Bit 192
Word 12 (16 bits)
Bit 256
Word 16 (16 bits)
Bit 320
Word 20 (16 bits)
Bit 384
Word 24 (16 bits)
Bit 448
Word 28 (16 bits)
Receive
Used
Used
Used
Not used
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